"Fons" wrote:...
> I only have one computer and FF3 keeps crashing when surfing some sites so I'd
> have FF2 one the working computer and FF3 on the playing one.

That is NOT a good enough excuse to buy another computer.

I have three versions of Firefox running at the moment. 2.0.0.14, 3.0, and 3.0.1pre,
I could be running with one version of Firefox and with different profiles, or Safe mode.
Only one profile can be in use at a time.

You can install each version of Firefox into it's own directory, make the choice with
custom install when you install Firefox. All profiles can be found together in a
directory which has advantages and disadvantages, but makes going to a specific
profile easy knowing where any one of them is at.

You can have only one default browser, which is the one that external applications
will find such as email. That default will/should start up automatically when you
click on a link in an external application such as mail, but not from any browser
which will find it's own links. My default browser is 3.0 at the moment, and
can easily be changed. I could bring up another 3.0 (perhaps in Safe Mode)
with a different profile (not the same profile) and that and other profiles would
be brought up with -no-remote on the startup command.

Create the Ultimate Firefox Web Development Profile :: the How-To Geek
http://www.howtogeek.com/howto/inter...pment-profile/

How to run multiple firefox profiles. on Technorati [ VIDEO ]
http://technorati.com/videos/youtube...%3D19WVImAQ6GU

Use Multiple Firefox Profiles at the Same Time :: the How-To Geek
http://www.howtogeek.com/howto/inter...the-same-time/

Profile: Finding and Assigning Shortcuts
http://www.mvps.org/dmcritchie/firef...e.htm#multiple

Command line arguments - MozillaZine Knowledge Base
http://kb.mozillazine.org/Command_line_arguments


--
HTH,
David McRitchie, extensions I use are briefly documented on my site
Firefox Custom: http://www.mvps.org/dmcritchie/firefox/firefox.htm